Photography in colors



Dec. 19, 1922. 1,439,035

K. E. STUART.

PHOTOGRAPHY IN COLORS.

FILED FEB. 7| 1920.

Patented Dec. 19, 1922.

UNITED STATI-:sv PATENT OFFICE.

KENNETH E. STUART, OF.MERION, PENNSYLVANIA.

PHOTOGRAPHY IN COLORS.

Application led February 7, 1920. Serial No. 356,934.

, tion and malnng the photographic exposure through said screen, whereby the light is subjected to selective 'absorption before reaching the sensitive emulsion. `As thls process is well-known, -I need `not describe it further. My invention consists 'in a more advantageous selection of colors for `said screen than has heretofore been known and in an improved method ofapplying them.

Figs. 1,2, 3, and 4, are diagrams illustrating respectively the colors chosen and the method of applying them in four typical embodiments of my invention. Figi 5 illustrates diagrammatically` the spectra of the colors used in Fig. 4. ig. 6 illustrates still another embodiment of my invention. It is to be understood that these colors are to be applied in the form of transparent bands to a suitable transparent back or support, as ,ofl glass or Celluloid (not shown).

It has heretofore been customary to use for the purposesof photographic color screens, such combinations as red, yellow and blue or red, green and blue-violet. The consef quence of this is that 1f a red area should accidentally overlap a green'or blue area little or no light canpass through them and the result isa dark spot. Such spots are often sufficient to ruin an otherwise line photo.

graph. In the case of ruled screens, the over` lap of the rulings results 1n ldark llnes which give rise to diffraction effects. The extreme care necessar i lines makes the manufacture of such plates expensive. The essential princ1ple of my 1nvention is the employment of colors any two of which may be super-posed without causing total absorption or black spots and Wh1ch are in fact intended to be so used.

overlap the purple lphotographic result that to avoid these dark spots or Referring now to F1 1, O, O indicate twoof a series of band (the width being greatly exaggerated), consisting of any suitable veh1cle, such-as Canada balsam, gelatine, etc., and dyed such a color as will transmit substantiallyall light rays from the red end of the spectrum low. The color effect of such a band to the eye will be orange.

P, P indicate similar bands .transmitting principally the red, blue and vlolet rays. These bands will appear purple or magenta.V It will be noticed that they overlap the orange bands for one half to and including yel-v of theirfwidth. IWhere such overlap occurs,

the blue, yellow' and violet rays will be absorbed, leaving only the red rays which may pass both bands. G, G indicate similar bands transmitting substantially all light from yellow to blue inclusive. pear green. They overlap the orange bands for one half of their width and the purple bands for the remainder of their width. Where the green bands overlap the orange the result will be a line transmitting only or. prlnclpally yellow, since that is the only colorv common to the two; and where they bands we will have blue for the same reason. Thus the final result 1s. a series of lines in Substantially red, yellow and blue, and these lines are only half the width of the bands. It is of course advantageousfrom the point of view of the the lines should be line, while 'itis of advantage from the point of View of manufacture that the bands should be as wide as practicable. Thus both of these desiderata are served at the `same time.

purple or magenta bands and G, G bands as before; but these bands are so as to overlap for only one third oftheir width. The result is thatthe lines produced green have only one third of the width ofthe complete spectrum. The principal advan- These bands will ap- In Fig.` 2, O, O indicate orange bands, P, P l

put on tage of this over the method of Fig. 1, is that the bands are still wider and there are no bands with contiguous edges.

If it is desired to obtain from the over-.

lapping bands resulting lines in orange-red, green, and blue-violet, which are the colors most largely used in the established processes, this can be done by the method illustrated in Fig. 3. In this case theapphed colors are blue-violet-red, or magenta as before; red-orange-yellow-green, or a color that will appear predominantly orange-yellow; and green-blue-violet, or to the eye blue-green. p

The range of the spectrum covered by these three applied colors respectively should be approximately for the blue-green, from 13,900 to 15,800; for the orange-yellow from 14,800 to 17,000; and for the-magenta, from 13,900 to 14,900 and from 15,700 to 17,000. The resultant lines will have the following color values: for the blue-violet 13,900 to 14,900; for the green 14,800 to 15,800; and for the orange-red 15,700 to 17,000.

My invention is not limited to the use of any particular dyes, as there are many suitable dyes commercially available.

Fig. 4 illustrates a simpliication of the method of Fig. 2. In this case, in order to reduce the number of applied colors from three to two, the colors used are minus redorange-yellow (i. e., such a`color as will transmit all rays but those from the red end of the spectrum to and including yellow) and minus blue-violet (or a color that will transmit all rays except blue and violet).

The overlapping of these bands will give green` since this is the only color common to both, so that with only two applied colors we have red-orange-yellow, green and bluegreen. To give the best result, the colors chosen, although they must contain green, should be somewhat weak inthis color. This is illustrated by the spectra of these two colors given in Fig. 5` in which the intensity ot' the color is indicated by the ordinate of the curve. It will be noticed in Fig. 4, that the green recurs twice as frequently as the other colors. Thus the weakness in this color which is necessary in order to bring out the other colors, is compensated for by providing a greater area for the passage of green light.

Fig. 6, is a modification in which two series of bands at right angles are used, giving squares instead of lines of color. In this case one series of bands consists of redorange-yellow and green-blue-violet respectively and the other series consists of orangeyellow-green and blue-violet-red respectively. The resultant squares are of red. green, blueviolet and orange-yellow.

It is to be understood that color screens made according to my invention may be used either between the glass plates or celluloid film and the sensitive emulsion or as a separate taking or viewing screen.

It will now be seen that my invention provides a color screen that can be applied to either glass plates or Celluloid films, including films for the production of moving pictures, by simple mechanical means, giving a cheaper and better method of photography in colors than any heretofore known.

In effect, I obtain a screen of substantially monochrome colors by the use of polychrome colors, subtractively applied (although additively employed in the subsequent photography) thus obtaining rich and natural rendering without the liability of black spots or other defects.

Having now described my invention, what I claim is:

l. A photographic color screen composed ofcolored bands having overlapping spectra.

2. A color screen composed of colored bands having color values in common.

3. A photographic color screen comprising twoV or more series of bands, said bands having color values in common.

4. A photographic color screen comprising two or more series of bands each band covering a range of the spectrum including two or more of the prismatic colors.

5. A photographic color screen comprising two or more series of overlapping bands of color.

` 6. A photographic color screen comprising two series of bands of color applied with a clearance between and a third series of bands of color applied so as to overlap the two bands first mentioned.

7. A photographic color screen comprising a series of bands transmitting principally red, blue and violet light, a second series of bands transmitting principally green, blue and violet light, and a third series of bands transmitted principally red. orange, yellow and green light.

8. A photographic color screen comprising a series of bands transmitting principally red, blue and violet light, a second series of bands transmitting principally green, blue and violet light and a third series of bands transmittlng principally red, orange, yellow and green light, said bands being applied so as to overlap. l

9. A photographic color screen comprising a series of parallel bands transmitting principally red, ,blue and Violet light, a second series of parallel bands transmitting principally green, blue and violet light'and a third series of parallel bands transmitting principally red, orange, yellow and green light, said bands being applied in regular sequence so as to overlap for one third or more of their width.

l0. A photographic color screen comprising two or more series of ing two or more series of parallel bands of color a plied with non-contiguous edges.

11. photographic color screen comprising. two or more series of parallel voverlapping bands `of color applied with non-contiguous edges. i 1

12. A photographic'color screen icomprisparallel overlapping bands of color, such bands where they overlap being in direct contact. 5

13.A A photographic 'color screen comprising two or more series of parallel overlapping bands, said bands appliedwith noncontiguous edges, such bands where they overlap being 1n direct contact.

14. A photographic color screen comprising a series of bands transmitting principally blue,violet and red light, a second series of bands transmitting principally green, blue and violet light and a third series of bands transmitting principally red, orange, yellow and green light, said bands applied with non-contiguous edges.

15. A photographic color screen comprising a series of bands transmitting principally blue, `violet and red light, a second series of bands transmitting principally green, blue and violet light, and a third series of bands transmitting principally red, orange, yellow and green light, said'bands applied with overlapping, nonconti uous edges, such bands where they overlap eingl p in direct contact.

Vtrum than that 16. A photographic color screen comprising two or more series of transparent polychrome bands, said bands being applied subtractively.

17. A photographic color screencompris-4 ing a plurality of polychrome bands, said bands being applied vso as to produce by subtraction the effect of substantially mono-l chrome bands.

18. A'photographic color screen comprising a plurality of polychrome bands, said bands being applied so as to produce bfy subtraction the eii'ect of bands transmittlng light covering a narrower range of the speccovered by said applled bands. t

19,-A photographic color screen compris- `ing a plurality of transparent colored bands,

eachl of said bands being adapted to vtransmit two or more of the prismatic colors, adjacent band's being super-posed for a part of their width.

.v 20. A photographic color screen comprising a series of transparent bands transmitting principally red, blue and violet light,

a second serles oftransparent bands trans-y mitting principally-red, orange, yellow, and.

green light, the bands of said second series Z overlapping those of said first series for part of their width, whereby a series of bands transmitting principallyvred light 1s produced and a third series of transparent bands transmitting principally green, blue and violet light, the bands of said third series overlapping those of said second series for part of their Width, whereby a series of bands transmitting principally green light is produced, the bands of said first series overlapping those of said third series for part of their width whereby a series of bands transmitting principally blue and violet produced adapted to transmit light of a narrower range of color values than said applied bands.

22. The method Vof preparing a colo-r screen -for photography in colors which consists in app ying two or more series of bands,

said bands being composed of transparent i vcolloidal material, each of said series being' dyed a color adapted to transmit polychrome light rays, said bands being overlapped without contiguous edges accordingto a definite pattern, whereby resultant areas are produced adapted to transmit light of a narrower .range of color values than said applied bands.

23. In a system of color photography, a color screen composed of colors adapted to be super-posed, whereby the difiiculty of accurately registering the applied colors is avoided.

24. In a system of color photography, a color screen composed of overlapping bands of color, whereby the resultant bands are narrower 4than the applied bands.

25. In a screen for color photography composed of app-lied colored bands any two of which may be super-posed witho-ut producing total absorption.

26. A photographic color screen comprising a series of bands transmitting rincipa ly a light ,from 3,900'to )r5,800 inc usive; a second series of bands transmitting principally light from M9800 to )t7 ,000 inclusive; and a third series of bands transmitting principally light from A3,900 to I\4,900 inclusive and from /\5,700 to /\7,000 inclusive.

27. A photographic color screen comprising a series of bands. transmitting principally light from 3,900 to 5,800 inclusive;I a second series of bands transmitting prinwhereby a series of lines transmitting principally light from )03,900 to 1,900 is produced.

In Witness whereof I have affixed my signature hereto this fifth day of February,

KENNETH E. STUART. 

